Dual mode heat exchanger assembly

ABSTRACT

A dual mode heat exchanger has a first and second manifold with a plurality of flow tubes fluidly connecting the manifolds for passing refrigerant between the manifolds. The first manifold is divided into at least two chambers. The second manifold defines a single cavity but can form more than one chamber. Separators divide the cavities and are offset from each other creating groups of flow tubes that connect one chamber in each manifold. At least one port in each chamber of one of the manifolds is in the open position for controlling refrigerant circulation. All of the ports are opened in one of the manifolds to permit refrigerant to pass through all of the plurality of tubes in at least one pass in evaporator mode. At least one of the ports is closed to permit refrigerant to pass through all of the plurality of flow tubes in at least two passes in condenser mode.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a dual mode heat exchanger assembly and a method of operating the heat exchanger assembly.

2. Description of the Prior Art

Dual mode heat exchanger assemblies operate in a condenser mode for cooling and an evaporator mode for heating. System operating requirements related to refrigerant phase, velocity and distribution vary between the condenser and the evaporator modes. In the evaporator mode, partially expanded two phase refrigerant enters the heat exchanger where the refrigerant continues to expand absorbing heat from the air. Momentum effects due to large mass differences between gas and liquid phase can result in separation of the phases. This two phase flow can result in poor refrigerant distribution in the heat exchanger assembly degrading performance in the evaporator mode and can cause icing/frosting of the core.

Dual mode heat exchanger assemblies and methods of addressing the differences in refrigerant flow characteristics, are known in the art. One approach involves modifying the pass arrangements depending on the mode of operation. This generally involves establishing a flow path length for circulating the refrigerant in the condenser mode and reducing the flow path length of the refrigerant in the evaporator mode, generally by bypassing some of the flow tubes that pass refrigerant between manifolds. Another method involves inclusion of distribution tubes, structures with a plurality of apertures, to facilitate the distribution of the refrigerant within the manifolds when the heat exchanger assembly is operating in the evaporator mode.

Examples of such assemblies are disclosed in Patent Application 2,409,510 A to Heys, U.K Patent Application 2,375,596 A to Heys, U.S. Pat. No. 5,826,649 to Chapp et al.

The Heys '510 Patent Application discloses a dual purpose heat exchanger assembly with an external bypass means of reducing the number of passes during the evaporator mode. The heat exchanger assembly uses one port to introduce refrigerant and one port to exit refrigerant from the heat exchanger assembly. The bypass means is associated with one of the manifolds, which, when open, connects the manifold with the port where refrigerant is introduced, to reduce the number of passes by at least one. This reduces the length of the flow path when the system is in evaporator mode reducing the pressure drop through the heat exchanger assembly and both improving efficiency and reducing ice formation on the heat exchanger assembly during the evaporator mode.

The Heys '596 Patent Application discloses a dual mode heat exchanger assembly with an external bypass means of reducing the number of refrigerant passes when the heat exchanger assembly is operating in the evaporator mode. This is for a vehicle air conditioning system including the heat exchanger assembly in the '510 patent.

The Chapp '649 Patent discloses a dual mode heat exchanger assembly and includes curved headers to address the problem of condensate on the outside of the plurality of tubes in the evaporator mode. There is a lower and upper header with a plurality of flow tubes running vertically. In the evaporation mode, the refrigerant enters the top manifold, drop through pipes to the lower manifold and is directed to the upper manifold through a jumper tube, more similar in diameter to the manifolds, where the refrigerant drops to the lower manifold and is exited through the outlet port. When operating in the evaporator mode, the refrigerant enters the lower manifold and follows exactly the reverse path. Valves inside the heat exchanger assembly can also be used to direct the flow of refrigerant. The path length is the same for each mode.

Current dual mode heat exchanger assemblies modify the pass arrangements by providing internal and external bypass means which avoid circulating refrigerant through all of the flow tubes in the heat exchanger, resulting in sub-optimal efficiency in both modes. An opportunity exists to provide a heat exchanger assembly and a method of operating the heat exchanger assembly, which optimizes heat exchange in both the evaporator and the condenser modes.

SUMMARY OF THE INVENTION AND ADVANTAGES

The subject invention provides a heat exchanger assembly having a first manifold and a second manifold each defining a hollow cavity, and in spaced and substantially parallel relationship with each other. A separator is disposed within the first manifold and divides the cavity of the first manifold into a first chamber and a second chamber. A plurality of flow tubes are fluidly connected to the first and second manifolds for passing refrigerant between the manifolds. A plurality of ports are connected to at least one of the first and second manifolds. Each of the ports have an open position for allowing refrigerant to flow into and out of the manifolds and a closed position for preventing refrigerant from flowing into and out of the manifolds. There is at least a first port, a second port, and a third port. An external controller switches the heat exchanger assembly between an evaporator mode and a condenser mode. At least one of the ports in each of the chambers and cavity of one of the manifolds is in the open position for circulating refrigerant through all of the plurality of flow tubes in at least one pass when the heat exchanger assembly is operating in the evaporator mode and at least one of the ports is in the closed position for circulating refrigerant through the plurality of flow tubes in at least two passes when the heat exchanger assembly is operating in the condenser mode.

The subject invention also provides a method of operating a heat exchanger assembly circulating the refrigerant through all of the plurality of flow tubes in at least one pass in the evaporator mode and in more than one pass in the condenser mode, including the following steps: opening one of the ports in each of the manifolds to define an evaporator mode; introducing refrigerant into one of the manifolds; passing the refrigerant through all of the plurality of tubes in a single pass; exiting the refrigerant from an opposing manifold; closing the third port of the second manifold to define a condenser mode; introducing the refrigerant into one of the chambers of each one of the manifolds to define an inlet chamber; passing the refrigerant through the plurality of tubes connected to the inlet chamber; passing the refrigerant into another chamber of one of the manifolds to define a mid-flow chamber; passing the refrigerant through the plurality of tubes connected to the mid-flow chamber; passing the refrigerant into another chamber of one of the manifolds to define an outlet chamber; and exiting refrigerant through the port connected to the outlet chamber.

The subject invention also provides a method of operating a heat exchanger assembly circulating the refrigerant through all of the plurality of flow tubes in at least two circuits and in more than one pass in the evaporator mode and in more than one pass in the condenser mode, including the following steps: opening at least one of the ports in one of the manifolds to define an evaporator mode; introducing the refrigerant into one of the manifolds to define an inlet chamber; passing the refrigerant through the plurality of flow tubes connected to the inlet chamber; passing the refrigerant into the opposing manifold to define a mid-flow chamber; passing the refrigerant through the plurality of flow tubes connected to the mid-flow chamber; passing the refrigerant into the opposing manifold to define an outlet chamber; exiting the refrigerant through the port connected to the outlet chamber; closing the fourth port and opening the third and fifth ports to define a condenser mode; introducing the refrigerant into the third port of the second manifold to define an inlet chamber; passing the refrigerant through the plurality of flow tubes connected to the inlet chamber; passing the refrigerant into the first chamber of the first manifold to define a first mid-flow chamber; passing the refrigerant through the plurality of flow tubes connected to the first mid-flow chamber; passing the refrigerant into the fourth chamber of the second manifold to define a second mid-flow chamber; passing the refrigerant through the plurality of flow tubes connected to the second mid-flow chamber; passing the refrigerant into the second chamber of the first manifold to define a third mid-flow chamber; passing the refrigerant through the plurality of flow tubes connected to the third mid-flow chamber; passing the refrigerant into the fifth chamber of the second manifold to define an outlet chamber; and exiting the refrigerant through the fifth port connected to the outlet chamber.

While current dual mode heat exchanger assemblies have different refrigerant flow paths depending on the mode of operation, this has been accomplished by bypassing a portion of the plurality of flow tubes. The subject invention optimizes heat exchange when the heat exchanger assembly is operating in both the evaporator mode as well as when the heat exchanger assembly is operating in the condenser mode, by using all of the plurality of flow tubes to circulate the refrigerant in one or more passes through the heat exchanger assembly when operating in the evaporator mode and circulating the refrigerant in more than one pass when the heat exchanger assembly is operating in the condenser mode.

BRIEF DESCRIPTION OF THE DRAWINGS

Other advantages of the present invention will be readily appreciated, as the same becomes better understood by reference to the following detailed description when considered in connection with the accompanying drawings wherein:

FIG. 1 is a perspective view of one embodiment of a heat exchanger assembly;

FIG. 1A is a schematic planar view of the embodiment of the heat exchanger assembly of FIG. 1 in an evaporator mode;

FIG. 1B is a schematic planar view of the embodiment of the heat exchanger assembly of FIG. 1 in a condenser mode;

FIG. 1C is a schematic planar view of the embodiment of the heat exchanger assembly of FIG. 1 illustrating a single pass refrigerant flow path in the evaporator mode;

FIG. 1D is a schematic planar view of the embodiment of the heat exchanger assembly of FIG. 1 illustrating a two pass refrigerant flow path in the condenser mode;

FIG. 2 is a perspective view of another embodiment of a heat exchanger assembly;

FIG. 2A is a schematic planar view of the embodiment of the heat exchanger assembly of FIG. 2 in an evaporator mode;

FIG. 2B is a schematic planar view of the embodiment of the heat exchanger assembly of FIG. 2 in a condenser mode;

FIG. 2C is a schematic planar view of the embodiment of the heat exchanger assembly of FIG. 2 illustrating a single pass refrigerant flow path in the evaporator mode;

FIG. 2D is a schematic planar view of the embodiment of the heat exchanger assembly of FIG. 2 illustrating a three pass refrigerant flow path in the condenser mode;

FIG. 3 is a perspective view of another embodiment of a heat exchanger assembly;

FIG. 3A is a schematic planar view of the embodiment of the heat exchanger assembly of FIG. 3 in an evaporator mode;

FIG. 3B is a schematic planar view of the embodiment of the heat exchanger assembly of FIG. 3 in a condenser mode;

FIG. 3C is a planar view of the embodiment of the heat exchanger assembly of FIG. 3 illustrating a single pass refrigerant flow path in the evaporator mode;

FIG. 3D is a schematic planar view of the embodiment of the heat exchanger assembly of FIG. 3 illustrating a four pass refrigerant flow path in the condenser mode;

FIG. 4 is a perspective view of another embodiment of a heat exchanger assembly with a distribution tube;

FIG. 4A is a schematic planar view of the embodiment of the heat exchanger assembly illustrating a two circuit, two pass refrigerant flow path in an evaporator mode;

FIG. 4B is a schematic planar view of the embodiment of the heat exchanger assembly illustrating a four pass refrigerant flow path in a condenser mode.

FIG. 4C is a schematic planar view of the embodiment of the heat exchanger assembly illustrating a two pass refrigerant flow path in the evaporator mode.

FIG. 4D is a schematic planar view of the embodiment of the heat exchanger assembly illustrating a four pass refrigerant flow path in the condenser mode.

FIG. 5 is a perspective view of another embodiment of a heat exchanger assembly with a distribution tube;

FIG. 5A is a schematic planar view of the embodiment of the heat exchanger assembly illustrating a two pass refrigerant flow path in an evaporator mode;

FIG. 5B is a schematic planar view of the embodiment of the heat exchanger assembly illustrating a four pass refrigerant flow path in a condenser mode.

FIG. 5C is a schematic planar view of the embodiment of the heat exchanger assembly illustrating a two pass refrigerant flow path in the evaporator mode;

FIG. 5D is a schematic planar view of the embodiment of the heat exchanger assembly illustrating a four pass refrigerant flow path in the condenser mode.

DETAILED DESCRIPTION OF THE INVENTION

Referring to the Figures, wherein like numerals indicate corresponding parts throughout the several views, a heat exchanger assembly is generally shown at 20 in FIGS. 1-1D. The heat exchanger assembly 20 includes a first manifold 22 and a second manifold 24. The first manifold 22 defines a cavity 26 and has a length and a width, substantially transverse the length, with a first end 48 and a second end 50, adjacent the length. The second manifold 24 is in spaced and substantially parallel relationship to the first manifold 22 and defines a cavity 27. The second manifold 24 has a length and a width, substantially transverse the length, with a first end 49 and a second end 51, adjacent the length. The second manifold 24 is shown throughout the drawings as having the same general appearance as that of the first manifold 22, however it can be readily appreciated that the first and second manifolds 22, 24 can have different dimensions, for example, the width of the second manifold 24 can be greater than the width of the first manifold 22. In addition, the construction of the manifolds 22, 24 can vary, for example, but not limited to, the first manifold 22 can comprise a single piece and the second manifold 24 can comprise multiple joined pieces. Similarly, it can be appreciated that though the manifolds 22, 24 are illustrated throughout the various drawings as generally cylindrical, the manifolds can take on a variety of shapes, for example but not limited to, the cross section of the manifolds 22, 24 at the width, can define a D-shape or a polygon.

A first separator 38 is disposed within the cavity 26 of the first manifold 22 dividing the first manifold 22 into a first chamber 40 and a second chamber 42. A substantially flat first separator 38 is shown which is disposed along the width of the first manifold 22, however, it can be readily appreciated that the first separator 38 can have a variety of cross-section shapes, such as, but not limited to, a crescent, and the first separator 38 can also be disposed within the cavity 26 in various ways, such as, but not limited to, diagonally forming acute and obtuse angles where the first separator 38 is adjacent the first manifold 22. It can further be appreciated that the first separator 38 can be constructed in a variety of ways, such as, but not limited to, being a portion of an insert slideably inserted within the cavity 26 or a single piece inserted through a cut in the first manifold 22. In addition, though the first separator 38 is shown approximately midway between the ends 48, 50 of the first manifold 22, it can be appreciated that the placement of the first separator 38 relative to the length of the first manifold 22 can vary. In addition, it can be readily appreciated that additional separators can be disposed within the first manifold cavity 26.

A plurality of flow tubes 28 extend between and fluidly connect the first and second manifolds 22, 24 for passing refrigerant between the manifolds 22, 24. It can be appreciated that additional heat dissipating structures, such as fins 29, can be included adjacent the plurality of flow tubes 28. The plurality of flow tubes 28 are substantially parallel to each other, and are generally transverse the length of the manifolds 22, 24. For purposes of illustration throughout the drawings, ten to twelve flow tubes are depicted, however it can be readily appreciated, that the number is not limited to those illustrated, but can vary based on the requirements of the heat exchanger assembly 20.

Groups of flow tubes 62, 64, 66, 68 are defined by flow tubes which are fluidly connected to the same chambers. Referring to FIG. 1A-1B, a first group 62 of flow tubes is fluidly connected to the first chamber 40 and the cavity of the second manifold 27. A second group 64 of flow tubes is fluidly connected to the second chamber 40 and the first cavity 27. The groups 62, 64 of flow tubes enable the serpentine circulation path of the refrigerant through the heat exchanger assembly 20.

A plurality of ports 30 are fluidly connected to at least one of the manifolds. 22, 24, and have an open position for allowing refrigerant into and out of the manifolds 22, 24 and a closed position for preventing the refrigerant from passing into or out of the manifolds 22, 24. An external tube is fluidly connected to each of the ports 30, and refrigerant passes through the external tubes to enter or exit the heat exchanger assembly 20. It can be readily appreciated that the external tubes can be joined directly to any portion of the manifold 22, 24 in a variety of ways, including but not being limited to, by a process such as brazing or welding. Alternatively, an attachment means such as a coupler can be disposed within the port 30, and the external tube inserted through the coupler to form the connection. It is understood that the plurality of ports 30 are illustrated throughout the figures as including the external tube as part of the port 30. It can further be understood that the term port 30 within the context of the present invention is intended to include other structures, such as couplers, where required by a specific application. It can be readily appreciated that for the present invention, when reference is made to the port 30 having a closed position, refrigerant does not enter or exit the manifold 22, 24 at that location. Similarly when a port 30 is in the open position, refrigerant enters or exits the heat exchanger assembly 20 through the port 30. An external controller restricts or permits the flow of refrigerant into the port 30, and the actual means is external to the heat exchanger assembly 20. A first port 92 is fluidly connected to the first chamber 40, a second port 94 is fluidly connected to the second chamber 42 and a third port 96 is fluidly connected to the cavity 27 of the second manifold 24. It can be appreciated that each port 92, 94, 96 can be used to either permit the refrigerant to enter or exit the heat exchanger assembly 20, depending on the configuration desired.

An external controller switches the heat exchanger assembly 20 between an evaporator mode 34 for heating and a condenser mode 36 for cooling. In the evaporator mode 34, the refrigerant is circulated through the heat exchanger assembly 20, absorbing heat from air passing over the plurality of flow tubes 28. As the refrigerant absorbs heat from the air, the refrigerant expands as liquid refrigerant is converted to gaseous refrigerant. In the condenser mode, the refrigerant in a gaseous state, enters the heat exchanger assembly 20 and heat is dissipated as the refrigerant is changed from the gaseous state to a liquid state. When operating in the evaporator mode 34, refrigerant is passed through all of the plurality of flow tubes 28 in one pass by opening at least one of the plurality of ports 30 in each of the chambers 40, 42 and cavities 27. In the condenser mode 36, at least one of the plurality of ports 30 is closed, for allowing the refrigerant to pass through all of the plurality of flow tubes 28 in more than one pass. It can be readily appreciated, that a number of alternative embodiments are possible, by varying the number of separators, the number of ports 30 and the configuration of open and closed ports 30.

Referring to FIG. 2, another embodiment is illustrated. A second separator 52 is disposed within the cavity 27 of the second manifold 24 forming a third chamber 56 and a fourth chamber 58. The second separator 52 is offset from the first separator 38. Referring to FIGS. 2A-2B, the third port 96 is fluidly connected to the third chamber 56 and a fourth port 98 is fluidly connected to the fourth chamber 58. Three groups of flow tubes are formed, including a first group 62 having flow tubes connected to the first chamber 40 and the third chamber 56, a second group 64 having flow tubes connected to the second chamber 42 and the third chamber 56, and a third group 66 having flow tubes connected to the second chamber 42 and the fourth chamber 58. In the evaporator mode 34, the first, second, third and fourth ports 92, 94, 96, 98 are in the open position for allowing the refrigerant to pass through all of the plurality of flow tubes 28 in one pass. In the condenser mode 36, the first and fourth ports 92, 98 are in the open position for passing the refrigerant through the heat exchanger assembly 20 in three passes.

Referring to FIG. 3, another embodiment is illustrated having having a third separator 54 disposed within the second manifold 24 further dividing the cavity 27 of the second manifold 24 into a fifth chamber 60. The second and third separators 52, 54 in the second manifold 24 are offset from the first separator 38 in the first manifold 22. Referring to FIGS. 3A-3B, four groups of flow tubes 62, 64, 66, 68 are formed, including, a first group 62 having flow tubes connected to the first chamber 40 and the third chamber 56, a second group 64 having the flow tubes connected to the first chamber 40 and the fourth chamber 58, a third group 66 having the flow tubes connected to the second chamber 42 and the fourth chamber 58, and a fourth group 68, having flow tubes connected to the second chamber 42 and the fifth chamber 60. In the evaporator mode 34, the first, second, third, fourth and fifth ports 92, 94, 96, 98, 100 are in the open position for allowing refrigerant to pass through the heat exchanger assembly 20 in one pass. In the condenser mode 36, the third and fifth ports 96, 100 are in the open position for passing the refrigerant through the heat exchanger assembly 20 in four passes.

Referring to FIG. 4, another embodiment is illustrated having no ports 30 connected to the first manifold 24. A third separator 54 is disposed within the second manifold 24 further dividing the cavity 27 of the second manifold 24 into a fifth chamber 60. The second and third separators 52, 54 in the second manifold 24 are offset from the first separator 38 in the first manifold 22. Referring to FIGS. 4A-4B, four groups of flow tubes 62, 64, 66, 68 are formed, including, a first group 62 having flow tubes connected to the first chamber 40 and the third chamber 56, a second group 64 having the flow tubes connected to the first chamber 40 and the fourth chamber 58, a third group 66 having the flow tubes connected to the second chamber 42 and the fourth chamber 58, and a fourth group 68, having flow tubes connected to the second chamber 42 and the fifth chamber 60. In the evaporator mode 34, the third, fourth and fifth ports 96, 98, 100 are in the open position for allowing the refrigerant to pass through the heat exchanger assembly 20 in one pass. In the condenser mode 36, the third and fifth ports 96, 100 are in the open position for passing the refrigerant through the heat exchanger assembly 20 in four passes.

Distribution tubes 70, 71 can be incorporated in the heat exchanger assembly 20 to facilitate distribution of the refrigerant in the evaporator mode 34. Referring to FIG. 4-4B, one embodiment is illustrated which includes a single distribution tube 70 disposed within the fourth chamber 58 of the second manifold 24. In the evaporator mode 34, the third, fourth and fifth ports 96, 98, 100 are in the open position. The refrigerant enters through the fourth port 98 which is directly connected to the distribution tube 70, and passes through the plurality of apertures disposed within the distribution tube 70, into the fourth chamber 58. In the condenser mode 36, the fourth port 98 is in the closed position and the third and fifth ports 96, 100 are in the open position. Refrigerant enters through the third port 96, and is circulated through the heat exchanger assembly 20, without being affected by the presence of the distribution tube 70 disposed within the fourth chamber. It can be readily appreciated that more than one distribution tube 70 can be included in the heat exchanger assembly 20.

Referring to FIG. 5A-B, another embodiment includes the first distribution tube 70 disposed within the third chamber 56 and a second distribution tube 71 disposed within the fifth chamber 60. A sixth port 102 is fluidly connected to the third chamber 56 and a seventh port 104 is fluidly connected to the fifth chamber 60. The third port 96 is fluidly connected to the first distribution tube 70 and the fifth port 100 is fluidly connected to the second distribution tube 71. The evaporator mode 34 is defined by the first, second, sixth and seventh ports 92, 94, 102, 104 being in the closed position and the third, fourth and fifth ports 96, 98, 100 being in the open position. The condenser mode 36 is defined by the sixth and seventh ports 102, 104 being in the open position and the first, second, third, fourth and fifth ports 92, 94, 96, 98, 100 being in the closed position. It can be readily appreciated that any number of distribution tubes 70, 71 and additional ports 30 can be incorporated into any design. It can also be readily appreciated that the same result would be accomplished where the first manifold 22 included no ports 30.

The various embodiments described previously can be generally described in the following way. There is at least a first port 92, a second port 94 and a third port 96. An external controller 32 switches between an evaporator mode 34 for heating and a condenser mode 36 for cooling. The first, second and third ports 92, 94, 96 are in the open position for circulating the refrigerant through all of the plurality of flow tubes 28 in n passes in the evaporator mode 34. In the condenser mode 36, at least one of the ports 30 is closed for circulating the refrigerant through all of said plurality of flow tubes 28 in at least n+l passes in the condenser mode 36 where said n is an integer equal to or greater than one. It can be readily appreciated that the structure described previously encompasses any number of chambers, flow tubes and ports 30, depending on the design requirements of the specific implementation. Similarly the schematics are merely illustrative. Any number of flow configurations in which refrigerant is introduced through different ports 30, for example, using the reverse flow of that illustrated in the figures, or mirror images, are equivalent to those discussed.

It can be further appreciated that distribution tubes 70, 71 can by included in any of the evaporator mode 34 inlet chambers 78. The distribution tubes 70, 71 are fluidly connected to the ports 30, and refrigerant passes through the apertures disposed within the distribution tubes 70, 71 into the evaporator mode 34 inlet chamber 78. It can also be appreciated that when the heat exchanger assembly 20 uses the evaporator mode 34 inlet chamber 78 as either a condenser mode 36 inlet or outlet chamber 78, 80, additional ports 30 can be fluidly connected to the condenser mode 36 inlet and outlet chambers 78, 80 for allowing refrigerant to enter and exit the heat exchanger assembly 20.

Two methods are described based on the structure described previously. The goal of all of the methods is the same, that is, to circulate the refrigerant in fewer passes in the evaporator mode 34 than in the condenser mode 36, while using all of the plurality of flow tubes 28 to circulate the refrigerant in each mode. Through the use of the external controller which controls the ports that are used for introducing and exiting the refrigerant, and by the configuration of the separators, a multitude of pass arrangements can be achieved. It can further be appreciated that the methods that follow, encompass more arrangements than are illustrated, and that the methods accommodate additional separators and ports, all of which permit variations in the arrangements while still being encompassed by the methods described here. In addition, it is understood that in methods which do not require that a manifold 22, 24 have a port in an open position to effectuate the refrigerant circulation, a manifold 22, 24 without any ports produces the same effect that a manifold 22 with all ports in the closed position, and is equivalent. Detailed descriptions of the methods and several embodiments follow.

Referring to FIGS. 1A-1D, a method of operating a heat exchanger assembly 20 is provided wherein the refrigerant circulates in one pass in the evaporator mode 34 and in at least 2 passes in the condenser mode 36. A heat exchanger assembly 20 has a first manifold 22 divided into a first chamber 40 and a second chamber 42 with a first port 92 and second port 94, a second manifold 24 defining at least one chamber with a third port 96, and a plurality of flow tubes 28 fluidly connecting the manifolds 22, 24. The method includes the step of opening one of the ports 30 in each chamber of the manifolds 22, 24 defining an evaporator mode 34. The method further includes introducing the refrigerant into one of the manifolds 22, 24, to define an inlet chamber 78. The method further includes passing the refrigerant through all of the plurality of flow tubes 28 in a single pass. The method further includes the step of passing the refrigerant into an opposing manifold 22, 24 defining an outlet chamber 80. The method further includes the step of exiting the refrigerant from a port connected to the opposing manifold 22, 24. The method further includes the step of closing the third port 96 of the second manifold 24 to define a condenser mode 36. The method further includes the step of introducing the refrigerant into one of the chambers of one of the manifolds 22, 24 to define an inlet chamber 78. The method further includes the step of passing the refrigerant through the plurality of flow tubes 28 connected to the inlet chamber 78. The method further includes the step of passing the refrigerant into another chamber of one of the manifolds 22, 24 to define a mid-flow chamber 72. The method further includes passing the refrigerant through the plurality of flow tubes 28 connected to the mid-flow chamber 72. The method further includes passing the refrigerant into another chamber of one of the manifolds 22, 24 to define an outlet chamber 80. The method further includes the step of exiting refrigerant through the port connected to the outlet chamber 80. The method allows refrigerant to pass through the heat exchanger assembly 20 in one pass when the heat exchanger assembly 20 is operating in the evaporator mode 34, and in more than one pass when the heat exchanger assembly 20 is operating in the condenser mode 36. It can be readily appreciated that the method encompasses heat exchanger assemblies 20 having manifolds 22, 24 with different numbers of chambers and ports.

This method is applied in the embodiment illustrated in FIGS. 1C-1D. The refrigerant is introduced into the first and second ports 92, 94, passes through all of the plurality of flow tubes 28 in a single pass, and is exited from the second manifold 24. To define the condenser mode 36 the third port 96 is closed. The refrigerant is introduced into the second chamber 42, and passes through the second group 64 of flow tubes into the third chamber 56. The refrigerant is then passed through the first group 62 of flow tubes into the first chamber 40. The refrigerant is then exited through the first port 92. It can be readily appreciated that when the heat exchanger 20 is operating in the evaporator mode 34, the refrigerant can alternatively be introduced through the third port 96 into the third chamber 56. Similarly, when the heat exchanger 20 is operating in the condenser mode 36, the refrigerant can be introduced through the first port 92 into the first chamber 40. It can be further appreciated that distribution tubes 70, 71 can by included in any of the evaporator mode inlet chambers 78. The distribution tubes 70, 71 are fluidly connected to the ports 30, and refrigerant passes through the apertures disposed within the distribution tubes 70, 71 into the evaporator mode 34 inlet chamber 78. It can also be appreciated that when the heat exchanger assembly 20 uses the evaporator mode 34 inlet chamber 78 as either a condenser mode 36 inlet or outlet chamber 78, 80, additional ports 30 can be fluidly connected to the condenser mode 36 inlet and outlet chambers 78, 80 for allowing refrigerant to enter and exit the heat exchanger assembly 20.

Referring to FIGS. 2A-2D, another embodiment of the method is described which allows the heat exchanger assembly 20 to circulate the refrigerant in one pass in the evaporator mode 34 and in at least three passes in the condenser mode 36. In addition to the structure described previously, this embodiment includes a fourth chamber 58 and a fourth port 98 fluidly connected to the fourth chamber 58. In addition to the steps described previously, the method further includes the step of closing the second port 94 of the first manifold 22 as well the third port 96 of the second manifold 24 and opening the first port 92 of the first manifold 22 and the fourth port 98 of the second manifold 24 to define the condenser mode 36. The method is the same for the evaporator mode 34 as in the previous embodiment. In the condenser mode 36, additional steps are required. After the refrigerant enters the mid-flow chamber 72, the refrigerant is passed through the plurality of flow tubes 28 connected to the mid-flow chamber 72. The method further includes passing the refrigerant into another chamber of one of the manifolds 22, 24 to define a second mid-flow chamber 74. The method further includes passing a refrigerant through the plurality of flow tubes 28 connected to the second mid-flow chamber 74. The method further includes passing the refrigerant into another chamber of one of the manifolds 22, 24 to define an outlet chamber 80. The method further includes the step of exiting refrigerant through the port connected to the outlet chamber 80. Thus, the method allows refrigerant to pass through the heat exchanger assembly 20 in one pass in the evaporator mode 34, and in three or more passes when the heat exchanger assembly 20 is operating in the condenser mode 36. It can be readily appreciated that the method encompasses heat exchanger assemblies 20 having manifolds 22, 24 with different numbers of chambers and ports.

This general embodiment is illustrated in a more specific embodiment illustrated in FIGS. 2C-2D. To define the evaporator mode 34, all of the ports 92, 94, 96, 98 in each of the manifolds 22, 24 are opened. The refrigerant is introduced into the first and second ports 92, 94, passes through all of the plurality of flow tubes 28 in a single pass, and is exited from the third and fourth ports 96, 98 of the second manifold 24. The condenser mode 36 is defined by closing the second and third port 94, 96. The refrigerant is introduced into the first chamber 40, passed through the first group 62 of flow tubes, into the third chamber 56. Refrigerant is then passed through the second group 64 of flow tubes into the second chamber 42. Refrigerant then passes through the third group 66 of flow tubes into the fourth chamber 58, and is exited through the fourth port 98. It can be readily appreciated that when the heat exchanger assembly 20 is operating in the evaporator mode 34, the refrigerant can alternatively be introduced through the third port 96 and fourth port 98 into the third and fourth chambers 56, 58, and exited through the first and second ports 92, 94 in the first manifold 22. Similarly, when the heat exchanger assembly 20 is operating in the condenser mode 36, the refrigerant can be introduced through the fourth port 98, passed into the fourth chamber 58, and exited through the first port 92 in the first chamber 40. In addition, it can be appreciated that distribution tubes 70, 71 can by included in any of the evaporator mode 34 inlet chambers 78. The distribution tubes 70, 71 are fluidly connected to the ports 30, and refrigerant passes through the apertures disposed within the distribution tubes 70, 71 into the evaporator mode 34 inlet chamber 78. It can also be appreciated that when the heat exchanger assembly 20 uses the evaporator mode 34 inlet chamber 78 as either a condenser mode 36 inlet or outlet chamber 78, 80, additional ports 30 can be fluidly connected to the condenser mode 36 inlet and outlet chambers 78, 80 for allowing refrigerant to enter and exit the heat exchanger assembly 20 in the condenser mode 36.

Referring to FIGS. 3A-3D, another embodiment of the method of operating a heat exchanger assembly 20 is provided wherein the refrigerant circulates in one pass in the evaporator mode 34 and in at least four passes in the condenser mode 36. The heat exchanger assembly 20 includes the elements of the previous embodiment, with the addition of a fifth chamber 60 disposed within the second manifold 24 and a fifth port 100 fluidly connected to the fifth chamber 60. The evaporator mode is the same as described in the previous embodiment. The condenser mode 36 is defined by the step of closing the first and second ports 92, 94 of the first manifold 22 and the fourth port 98 of the second manifold 24 to define a condenser mode 36. The method further includes the step of introducing the refrigerant into one of the chambers of one of the manifolds to define an inlet chamber 78. The method further includes the step of passing the refrigerant through the plurality of flow tubes 28 connected to the inlet chamber 78. The method further includes the step of passing the refrigerant into another chamber of one of the manifolds 22, 24 to define a first mid-flow chamber 72. The method further includes passing the refrigerant through the plurality of flow tubes 28 connected to the first mid-flow chamber 72. The method further includes the step of passing the refrigerant into another chamber of one of the manifolds 22, 24 to define a second mid-flow chamber 74. The method further includes passing the refrigerant through the plurality of flow tubes 28 connected to the second mid-flow chamber 74. The method further includes the step of passing the refrigerant into another chamber of one of the manifolds 22, 24 to define a third mid-flow chamber 76. The method further includes passing the refrigerant through the plurality of flow tubes 28 connected to the third mid-flow chamber 76. The method further includes passing the refrigerant into another chamber of one of the manifolds 22, 24 to define an outlet chamber 80. The method further includes the step of exiting refrigerant through the port connected to the outlet chamber 80. The method allows refrigerant to pass through the heat exchanger assembly 20 in one pass when the heat exchanger assembly 20 is operating in the evaporator mode 34, and in four or more passes when the heat exchanger assembly 20 is operating in the condenser mode 36. It can be readily appreciated that the method encompasses heat exchanger assemblies 20 having manifolds 22, 24 with different numbers of chambers and ports.

This general embodiment is illustrated in a more specific embodiment illustrated in FIGS. 3C-3D. The evaporator mode is defined by opening all of the ports 92, 94, 96, 98, 100 in each of the manifolds 22, 24. The refrigerant is introduced into the first and second ports 92, 94, circulated through all of the plurality of flow tubes 28 in a single pass, and exited from the third, fourth and fifth ports 96, 98, 100. The condenser mode is defined by closing the first, second and fourth ports 92, 94, 98. The refrigerant is introduced through the third port 96 into the third chamber 56, and passed through the first group 62 of flow tubes, into the first chamber 40. The refrigerant passes through the second group 64 of flow tubes into the fourth chamber 58. The refrigerant passes through the third group 66 of flow tubes into the second chamber 42. The refrigerant passes through the fourth group 68 of flow tubes into the fifth chamber 60, and is exited through the fifth port 100. It can be readily appreciated that when the heat exchanger 20 is operating in the evaporator mode 34, the refrigerant can alternatively be introduced through the third, fourth and fifth ports 96, 98, 100 of the second manifold 24, and exited through the first and second ports 92, 94 of the first manifold 22. Similarly, when the heat exchanger 20 is operating in the condenser mode 36, the refrigerant can be introduced through the fifth port 100 into the fifth chamber 60, and exited through the third port 96 connected to the third chamber 56. It can be readily appreciated that this method encompasses any number of passes in the evaporator mode and in the condenser mode. In addition, it can be appreciated that distribution tubes 70, 71 can by included in any of the evaporator mode inlet chambers 78. The distribution tubes 70, 71 are fluidly connected to the ports 30, and refrigerant passes through the apertures disposed within the distribution tubes 70, 71 into the evaporator mode 34 inlet chamber 78. It can also be appreciated that when the heat exchanger assembly 20 uses the evaporator mode 34 inlet chamber 78 as either a condenser mode 36 inlet or outlet chamber 78, 80, additional ports 30 can be fluidly connected to the condenser mode 36 inlet and outlet chambers 78, 80 for allowing refrigerant to enter and exit the heat exchanger assembly 20.

Referring to FIGS. 4A-4D, another method for operating a heat exchanger assembly 20 is provided where the refrigerant is divided into more than one circuit and passes through the heat exchanger assembly 20 in at least two passes in the evaporator mode 34. In this method, in the condenser mode 36, the refrigerant passes through the heat exchanger assembly 20 in four or more passes, as previously described and being illustrated at FIG. 3D, and will not be described again here. The heat exchanger assembly 20 has a first manifold 22 divided into a first chamber 40 and a second chamber 42 and a second manifold 24 defining a third chamber (56), a fourth chamber (58) and a fifth chamber (60), with a third port (96), a fourth port 98, a fifth port 100 and a plurality of flow tubes 28 fluidly connecting the manifolds 22, 24. The method includes the step of opening all of the ports 30 in the second manifold 24 to define an evaporator mode 34. The method further includes the step of introducing the refrigerant into at least one chamber of the second manifold 24 to define an inlet chamber 78. The method further includes the step of passing the refrigerant through the plurality of flow tubes 28 connected to the inlet chamber 78. The method further includes the step of passing the refrigerant into the first manifold 22 to define a first and second mid-flow chamber 72, 74. The method further includes the step of passing the refrigerant through the plurality of flow tubes 28 connected to the first and second mid-flow chambers 72, 74. The method further includes the step of passing the refrigerant into the second manifold 24 to define at least one outlet chamber 80. The method further includes the step of exiting the refrigerant through the port connected to the outlet chamber 80. It can be readily appreciated that the method encompasses more complex heat exchanger assemblies 20 requiring more than two circuits as well as more than two passes for the circulation of the refrigerant.

One embodiment of this method is illustrated in FIGS. 4C-4D. The evaporator mode 34 is defined by opening all of the ports 96, 98, 100 in the second manifold 24. The refrigerant is introduced into the fourth chamber 58 of the second manifold 24, where it is separated into a first portion and a second portion. The first portion of the refrigerant passes through the second group 64 of flow tubes into the first chamber 40, through the first group 62 of flow tubes into the third chamber 56, and is exited through the third port 96. Similarly, the second portion passes through the third group 66 of flow tubes, into the second chamber 42, through the fourth group 68 of flow tubes into the fifth chamber 60, and is exited from the fifth port 100. It can be readily appreciated that the refrigerant can be introduced through the third and fifth ports 96, 100 and exited through the fourth port 98, thus creating more than one inlet chamber 78, 79 and one outlet chamber 80. It can also be readily appreciated that the same flow path is possible by closing all of the ports 30 of the first manifold 22 in embodiments which include ports 30 in the first manifold 22. In addition, it can be appreciated that distribution tubes 70 can by included in any of the evaporator mode 34 inlet chambers 78. The distribution tube 70 is fluidly connected to the port 30, and refrigerant passes through the apertures disposed within the distribution tubes 70, 71 into the evaporator mode inlet chamber 78. Here, the distribution tube 70 is illustrated as being disposed within the fourth chamber 58. It can also be appreciated that when the heat exchanger assembly 20 uses the evaporator mode 34 inlet chamber 78 as either a condenser mode 36 inlet or outlet chamber 78, 80, additional ports 30 can be fluidly connected to the condenser mode 36 inlet and outlet chambers 78, 80 for allowing refrigerant to enter and exit the heat exchanger assembly 20.

Referring to FIGS. 5A-5D, an embodiment is illustrated including distribution tubes 70, 71 in chambers used as both evaporator mode inlet chambers and condenser mode 36 outlet chamber 80 and the condenser mode 36 inlet chamber 78. Here the evaporator mode 34 is defined by opening the third, fourth and fifth ports 96, 98, 100. A first portion of the refrigerant is introduced into the third port 96 and a second portion of the refrigerant into the fifth port 98. The first portion of the refrigerant passes through the first distribution tube 70 into the third chamber 56. The refrigerant then passes through the first group 62 of flow tubes, into the first chamber 40, through the second group 64 of flow tubes into the fourth chamber 58. Similarly, the second portion passes into the second distribution tube 71, into the fifth chamber 60, through the fourth group 68 of flow tubes, into the first chamber 40, through the third group 66 of flow tubes, and into the fourth chamber 58. All of the refrigerant is then exited through the fourth port 98. The condenser mode 36 is defined by closing the first, second, third, fourth and fifth port 92, 94, 96, 98, 100 and opening the sixth and seventh ports 102, 104. The refrigerant is introduced through the seventh port 104 into the fifth chamber 60, passes through the fourth group 68 of flow tubes, and into the second chamber 42. The refrigerant then passes through the third group 66 of flow tubes, into fourth chamber 58. The refrigerant then passes through the second group 64 of flow tubes, into the first chamber 40, and through the first group 62 of flow tubes into the third chamber 56. The refrigerant is exited through the sixth port 102. It can be readily appreciated that when the heat exchanger 20 is operating in the condenser mode 36, the refrigerant can alternatively be introduced into the sixth port 102 and exited through the seventh port 104.

Obviously, many modifications and variations of the present invention are possible in light of the above teachings without departing from the essential scope thereof. Therefore, it is intended that the invention not be limited to the particular embodiment disclosed, but that the invention will include all embodiments falling within the scope of the appended claims. The reference numerals are merely for convenience and are not to be read in any way as limiting. 

1. A heat exchanger assembly comprising: a first manifold and a second manifold each defining a hollow cavity and in spaced and substantially parallel relationship with each other; a plurality of flow tubes extending between and fluidly connecting said first and second manifolds for passing refrigerant between said manifolds; a separator disposed within said first manifold and dividing said cavity into a first chamber and a second chamber; a plurality of ports fluidly connected at least one of said first and second manifolds with each of said ports having an open position for allowing refrigerant to flow into and out of said manifolds and a closed position for preventing refrigerant from flowing into and out of said manifolds with said plurality of ports including at least a first port, a second port, and a third port; an external controller for switching between an evaporator mode and a condenser mode; and one of said ports in each chamber and cavity of one of said manifolds being in said open position for circulating refrigerant through all of said plurality of flow tubes in at least one pass when in said evaporator mode and at least one of said ports being in said closed position for circulating refrigerant through said plurality of flow tubes in at least two passes when in said condenser mode.
 2. An assembly as set forth in claim 1 wherein said first port is connected to said first chamber said second port is connected to said second chamber and said third port is connected to said cavity of said second manifold.
 3. An assembly as set forth in claim 2 wherein said evaporator mode is further defined by at least one of said ports in each chamber of said first manifold and at least one of said ports in said cavity of said second manifold being in said open position for circulating refrigerant in one pass.
 4. An assembly as set forth in claim 2 wherein said condenser mode is further defined by said first port and said second port being in said open position and said third port being in said closed position for circulating refrigerant in two passes.
 5. An assembly as set forth in claim 2 wherein said separator is further defined as a first separator and further including a second separator disposed within said cavity of said second manifold dividing said cavity of said second manifold into a third chamber and a fourth chamber.
 6. An assembly as set forth in claim 5 wherein said second separator is offset from said first separator with said first chamber fluidly connected to said third chamber through a first group of said flow tubes, said second chamber fluidly connected to said third chamber by a second group of said flow tubes, and said second chamber fluidly connected to said fourth chamber by a third group of said flow tubes.
 7. An assembly as set forth in claim 5 further including a fourth port connected to said fourth chamber with said first, second, third, and fourth ports being in said open position when in said evaporator mode for circulating refrigerant in one pass.
 8. An assembly as set forth in claim 7 wherein said condenser mode is further defined by said first port and said fourth port being in said open position and said second port and said third port being in said closed position for circulating refrigerant in three passes.
 9. An assembly as set forth in claim 2 wherein said separator is further defined as a first separator and further including a second and a third separator disposed within said second manifold dividing said cavity into a third, fourth and fifth chamber.
 10. An assembly as set forth in claim 9 wherein both of said second and third separators are offset from said first separator with said first chamber fluidly connected to said third chamber by a first group of said flow tubes, said first chamber fluidly connected to said fourth chamber by a second group of said flow tubes, said second chamber fluidly connected to said fourth chamber by a third group of said flow tubes, and said second chamber fluidly connected to said fifth chamber by a fourth group of said flow tubes.
 11. An assembly as set forth in claim 9 further including a fourth port connected to said fourth chamber and a fifth port connected to said fifth chamber with said first, second, third, fourth, and fifth ports being in said open position when in said evaporator mode for circulating refrigerant in one pass.
 12. An assembly as set forth in claim 11 wherein said condenser mode is further defined by said first port said second port and said fourth port being in said closed position and said third port and said fifth port being in said open position for circulating refrigerant in four passes.
 13. An assembly as set forth in claim 1 wherein said separator is further defined as a first separator and further including a second separator and a third separator disposed within said second manifold dividing said cavity into a third, fourth and fifth chamber.
 14. An assembly as set forth in claim 13 wherein both of said second and said third separators are offset from said first separator with said first chamber fluidly connected to said third chamber by a first group of said flow tubes, said first chamber fluidly connected to said fourth chamber by a second group of said flow tubes, said second chamber fluidly connected to said fourth chamber by a third group of said flow tubes, and said second chamber fluidly connected to said fifth chamber by a fourth group of said flow tubes.
 15. An assembly as set forth in claim 13 further including a third port connected to said third chamber and a fourth port connected to said fourth chamber and a fifth port connected to said fifth chamber and with said third, fourth and fifth ports being in said open position when in said evaporator mode for circulating refrigerant in two passes.
 16. An assembly as set forth in claim 15 wherein said condenser mode is further defined by said fourth port being in said closed position and said third port and said fifth port being in said open position for circulating refrigerant in four passes.
 17. An assembly as set forth in claim 1 including a distribution tube disposed within one of said chambers and said cavity with said distribution tube having a plurality of apertures and with said distribution tube being fluidly connected to one of said plurality of ports for passing refrigerant from one of said plurality of ports into at least one of said chambers and said cavity and further defining an evaporator mode inlet chamber.
 18. An assembly as set forth in claim 17 including a fourth port fluidly connected to said evaporator mode inlet chamber for circulating the refrigerant in said condenser mode.
 19. A method of operating a heat exchanger having a first manifold divided into a first chamber and a second chamber with a first port and second port, a second manifold defining at least one chamber with a third port, and a plurality of flow tubes fluidly connecting the manifolds, said method comprising the steps of: opening one of said ports in each chamber of said manifolds to define an evaporator mode; introducing refrigerant into one of the manifolds defining an inlet chamber; passing the refrigerant through all of the plurality of flow tubes in a single pass; exiting the refrigerant from an opposing manifold; closing the third port of the second manifold to define a condenser mode; introducing the refrigerant into one of the chambers of one of the manifolds to define an inlet chamber; passing the refrigerant through the plurality of flow tubes connected to the inlet chamber; passing the refrigerant into another chamber of one of the manifolds to define a mid-flow chamber; passing the refrigerant through the plurality of flow tubes connected to the mid-flow chamber; passing the refrigerant into another chamber of one of the manifolds to define an outlet chamber; and exiting the refrigerant through the port connected to the outlet chamber.
 20. A method of operating a heat exchanger having a first manifold divided into a first chamber and a second chamber and a second manifold divided onto a third chamber, a fourth chamber and a fifth chamber, with a third port, a fourth port, a fifth port and a plurality of flow tubes fluidly connecting the manifolds, said method comprising the steps of: opening at least one of the ports to define an evaporator mode; introducing the refrigerant into one of the manifolds to define an inlet chamber; passing the refrigerant through the plurality of flow tubes connected to the inlet chamber; passing the refrigerant into the opposing manifold to define a mid-flow chamber; passing the refrigerant through the plurality of flow tubes connected to the mid-flow chamber; passing the refrigerant into the opposing manifold to define an outlet chamber; exiting the refrigerant through the port connected to the outlet chamber; closing the fourth port and opening the third and fifth ports to define a condenser mode; introducing the refrigerant into the third port of the second manifold to define an inlet chamber; passing the refrigerant through the plurality of flow tubes connected to the inlet chamber; passing the refrigerant into the first chamber of the first manifold to define a first mid-flow chamber; passing the refrigerant through the plurality of flow tubes connected to the first mid-flow chamber; passing the refrigerant into the fourth chamber of the second manifold to define a second mid-flow chamber; passing the refrigerant through the plurality of flow tubes connected to the second mid-flow chamber; passing the refrigerant into the second chamber of the first manifold to define a third mid-flow chamber; passing the refrigerant through the plurality of flow tubes connected to the third mid-flow chamber; passing the refrigerant into the fifth chamber of the second manifold to define an outlet chamber; and exiting the refrigerant through the fifth port connected to the outlet chamber. 